Thermostatic relay



Dec, 17, 1946. G. c. ARMSTRONG I 2,412,854

THERMOS TATI C RELAY Fild March 8, 1944 2 Sheets-sheaf 2 WITNESSES: INVENTOR Ga e c. Armstrazy.

ATTORNEY Patented Dec. 1, v v 2 412 5 "UNlTED STATE-S] PATENT OFFICE 2,412,854 THERMOSTATIC RELAY George C. Armstrong,-Wllldnsburg, Pa, asslgnor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 8, 1944, Serial No. 525,541-

. Claims (Ci. M -2) 1 I 2 My invention relates to thermally operating device of the type mentioned with a rotarymemelectric overload relays and other electric devices her which is spring biased for rotation in one diin which a spring biased movable member is norrection and normally retained against this bias mally prevented from following its bias and is by two thermostats arranged on opposite axial released electrically upon the occurrence of a 5 sides of the rotary member for thermoresponsive given release condition. deflection in the same axial direction. The two It is an object or the invention to provide despring biased thermostats engage the member so vices of the just-mentioned type with heat-reas to secure it normally in a given an ular posisponsive clutching and release means of improved tion regardless of changes in the ambient temdesign and operation. More particularly, the inlo perature, since such changes deflect both thermo-' vention aims at providing overload relays with stats equally and hence do not loosen their grip releasable clutching means of great reliability. on e ota y membe One or the thermostats is sensitivity, and accuracy of operation which are p o id d with ectri heating means w c whe also distinguished byextremely small spac resufllciently energized, cause it to deflect to a quirements. It is also an object to design a device 16 large! x ent than the other thermostat. A staof the type above referred to in such a manner tionary stop is provided which, upon excessive dethat the releasable latching or clutching means flection of the electrically heated thermostat, is act along the entire periphery of the movable reengaged by one 0! the thermostats and thereby lay member t be t h so as t be capable of renders the thermostats ineffective as regards exerting a considerable holding force thereon; 20 their grip n the r t y m mber- As a result, the and it is further aimed at achieving thi result member is released for rotation under its spring while requiring only a slight movement of the bias. clutch or latch means for efiecting the release The invention, in another aspect, involves the of the movable member. provision of two parallel plungers which engage Another object of my invention is to provide a the rotary relay member at radially opposite sides relay or other device of the type mentioned which and are approximately balanced as regards the is capable of withstanding extremely high impact axis 01' rotation so as to render the relay subl'orces or vibrations such as occurring under sh0ck, stantlally shockproof. and which does not terid to perform uncontrolled These and other features of th invention will operations whenexposedto such shock forces. In be understood from the following description of particular, it is intended by this invention to proth m i f thermostatic v l ad r y vide a thermostatic contactor that, when exposed illustrated in the drawings, in which:

to shock, does not release its contact member or i r 1 1 a top V w Of he, Ov rlo d r y; to otherwise change the contact position occu- Fig. 2 a view from one axial side of the relay; and pied previous to the shock. Fig. 3 a view from the other side;

An object is also the provision of-a device which 18- 4 represents an a l 8 17 0 ta along is shock-proof in the manner Just mentioned by the Plane denoted in 3 by e d ndh virtue of its inherent mechanical properties, that lines marked is, without necessitating the use of additional Fig. 5 is a cross-section taken along the plane shock or vibration responsive latching devices. 40 denoted in Fig. 1 by the dot-and-dash lines A still further object of the invention is to deed vise a, contactor, relay, or the like apparatus Fig. 6 is a partial sectional "18W similar to Fig.

which, while protected from undesired operation 4 Showing the h s c mechanism of the redue to shock, is, nevertheless, capable of intenlay in a condition occurring under a hi h mbient tional or desired operation during the periods of temperature the effect e ng x g erated for expersistence of shock forces or motions. Dlflnatory a n and In other aspects, my invention aims at a 0011- Fig. 7 is another cross-section through part of struction of an electric overload relay which, in he de i t en a o the plan denoted in Figconjunction with one or several of the aforemen- 4 y th d -and-dash line marked VII-VII.

tioned objects, is also distinguished by insensitiv- According to the drawings, the illustrated v ity to changes in ambient temperature and aflords load relay has an insulating may accomadjusting its datum value of release within wide modatine all other ent lay parts. The limits of overload currents. body I has a cylindrical cavity 2 which extends In order to achieve these objects and in accordaxially through the major portion of the body. ance with my invention, I provide a relay or other to This cavity communicates with two tangential circuit thereto. The two aeiaese bores 3 and ii which extend in parallel to each other and are open towards the top surface of the body i. Two lateral openings 6 and 8 (Figs. 1 and 4) are provided for mounting the relay on a suitable'support. The cylindrical cavity 2 has two diametrical projections l and 8 (Figs. 4 and 7) and the tangential bores 3 and 3 have radial extensions or grooves a and iii (Figs. 4 and 5).

A contact terminal surface of the insulating body 9 (Figs. 1 and 2) and carries a stationary contact 02. A second terminal is also mounted on the top surface of the insulating body carriesa pivot pin i An upwardly extending part i5 is attached to body 9. A contact lever it is pivotally mounted on pin it and carries a contact ill to cooperate with the stationarycontact l2. A helical compression spring 28, disposed between part it and contact lever i5, biases the lever towards the contact closing position shown in Figs. 1 and 2.

The contact lever it is controlled by a plunger it arranged in the bore 3 of the insulating body. The plunger has a radial projection 2% which engages the groove it, and hence prevents the plunger from rotating while permitting it to reciprocate along the bore. The plunger carries a push button is and has an inclined surface portion at an engaged by the contact lever it. A- helical compression spring "2.9, located underneath the plunger it in bore 31, tends to move the plunger in the upward direction (Fig. 5). The plunger has a toothed or rack-shaped portion which engages the toothed portion of a drum 36. Hence, when the push button it is in the depressed position shown in Figs. 1 and 5, the drum 36, when clutched against rotation, will maintain the plunger and push button in the illustrated position, so that the contacts 02 and it remain closed. It will be apparent that the spring 29 exerts a bias on the drum 3% tending to rotate this drum in the anti-clockwise direction. Hence, when the drum is released, it will rotate-in this direction while the plunger it moves upwardly. Such upward motion has the efiectof moving the inclined surface portion 28 along the contact lever iii, thereby pushing the lever i6 radially away from the plunger in opposition to the bias of spring 28 (Fig. 1). As a result, the contacts i2 and ii are opened during the just mentioned upward motion of the plunger.

The insulating body i is further provided with two contact terminals 2i and 22 both arranged on the top surface of the body and provided with binding posts for connecting the leads of the main terminals 23 and 2d of a heating winding 25 are attached to therespective terminals 2i and 22. The effective portion of the heater 25 extends of the insulating body (Fig. 4) and serves to operate the clutch mechanism to be described presently.

The clutch'mechanism for holding the contact actuating plunger in its depressed position comprises a shaft 30 which carries a sleeve 3i screwed onto the shaft. A radially projecting bearing portion 32 of the sleeve forms a circumferential stop surface at 33 and serves as a bearing for the above-mentioned clutch drum 35. This drum has axially projecting flange portions 37 and so and is provided with a toothed or geared portion 39 for engagement by the rack-shaped surface portion of the plunger l8.

Two thermostats 38 and ii are disposed at axially opposite sides of the clutch drum 8%. These thermostats, in the illustrated embodiinto the cavity 2 ment, consist each of a group of thin bimetal discs whose shape is best apparent from Fig.6. These discs have two diametrical notches for engagement by the projections l and d of the insulating body i. Due to this engagement, the theme-=- static discs are permitted to shift amally along the cylindrical cavity 2, but are prevented from rotating relative to the body i. The two thermostats (lii and ii engage the adjacent flange portions 8? and 38, respectively, of the clutch drum 3%. The thermostat lid is held in position by means of a lock nut '32 scrwed onto the shaft 3h. Since this shaft is in threaded engagement with the sleeve 3i, and the latter firmly secured to the insulating body i by means of nuts 38, and 35, the central portion of the thermostat id is prevented from moving in the upward direction (Fig. 4). The thermostat M is pressed against the lower flange 3d of drum; at by means of a helical compression spring at. It will be noted from Fig. 4 that the peripheral stop surface 33 of sleeve at is usually in proximity to-the thermostat dl, a small gap being maintained between the stop surface and the thermostat. This gap can be adjusted or varied by revolving the shaft Elli, thus threading it more or less into the sleeve 89 and thereby raising or lowering the loci; nut 62 and, hence, the entire spring biased clutch mechanism. In order to permit such an adjustment, a star wheel id is firmly mounted on the shaft at (Figs. 2 and 4) the star wheel lid, and permits fastening it in a selected position.

The above-mentioned heating winding 2% lies close to the thermostatic disc K d and hence, when heated by sumcient electric current, will affect this upper thermostat to a considerably greater extent than the lower thermostat ii. However, both thermostats respond substantially equally to gradual increases in ambient temperature, since the latter affects all parts of the relay to substantially the same extent.

Disregarding for the present the fact-that another plunger, denoted by Lid (Fig. 5) is present, the operation of the above-described parts of the overload relay is as follows. In normal condition, the clutch spring d3 presses the thermostat fill against the clutch drum 36 and the latter against the thermostat d0 whose upwar'd motion bend outwardly in the same is stopped by the lock nut d2. As a result, the friction acting circumferentially between the drum 36 and the two thermostats prevents the drum from following the rotary bias exerted by spring 29 when the plunger i3 is in the illustrated depressed position with relay contacts l2 and ill closed, as shown in Figs. 1 and 5. When the relay is exposed to increasing ambient temperatures, the two bimetal thermostats it and M will degree-for instance, as shown in Fig. 6. Since the central portion of thermostat 36 remains fixed, relative to body i, due to its abutment against the lock nut 132, the concurrent deflection of both thermostats has the effect of shifting the clutch drum 3% upwardly along. its seat 32. However, since the distance between corresponding points of the two thermostats remains unchanged, the central portion of the thermostat it remains at the original distance from the stop surface 33. Consequently, the clutch spring 33 remains effective and continues to press the thermostats against the clutch drum 3%. Therefore, a change in ambient tem= perature will not release the frictional grip of the thermostats on the drum, and hence cannot affeet the operation of the relay.

A set screw G5 engages given magnitude, the heating eflect of -36. The bore n the other hand, if the current supplied to terminals 2| and 22, and controlled by the relay contact between I! and I! (Fig. 1), exceeds a winding 25 causes the upper thermostat 40 to deflect considerably more than the lower thermostat 4! (Figs. 4 and 7). As a result, the distance between corresponding points of the two thermostats increases and the central portion of thermostat 4I' abuts against the stationary stop surface 33. This stops the further action of the clutch spring 43 so that the continued deflection of thermostat 40 has the efiect of removing the thermostat from the clutch drum, thereby releasing itsfrictional grip. As a result, the clutch drum and the plunger l8 are free to move under the bias of spring 29 (Fig. 5). The inclined surface 20 moves the contact lever i6 and opens contacts I2 and I1 -(Fig. 1). This causes an interruption of the main current or produces some other control action by means of a contactor (not illustrated) actuated by the opening of contacts l2 and l1.

The second plunger 46, provided in. the tangential bore 4 of the insulating body I (Figs. 4 and 5), has a mass corresponding substantially to the total mass of the plunger l8 and push button it. A radial projection 41 of plunger 46 engages the groove l0 and thus prevents the plunger from rotating. A rack-shaped surface portion of plunger 46 engages the gearportion 39 of the clutch drum 4 is covered by a stopper 48 which may also serve as a stop for limiting the upward motion of the plunger 46. It will be apparent from Fig. 5 that the plunger 46 moves simultaneously with the actuating plunger it, but always in the opposite direction.

During the normal operation of the relay, as described above, the plunger 46 has no operative effect except that it may serve as a stop for limiting the upward or downward motion or both of the actuating plunger i8. However, when the relay is exposed to shock or vibration, the second plunger has a balancing efiect and prevents such disturbing forces from operating the relay. When a shock force occurs, such force may be transmitted to the clutch mechanism substantially in three different ways. One possibility of shock transmission is given by the shaft and sleeve assembly of the clutch due to a back, front or side blow, Fig. 1. Any force transmitted through the axial direction spects by those skilled in the art without departing fromthe objects and gist of the invention, I wish this specification to be understood as illustrative and not in a limiting sense.

I claim as my invention:

1. A heat-responsive and ambient-temperature compensated relay comprising a rotary and axially displaoeable member spring biased for rotation,

two thermostats axially movable in the same di-.

rection in response to heat and disposed for normally engaging said rotary member at axially opposite sides so as to prevent it, when moved against its spring bias, to perform a return motion under said bias, stationary stop means forable relative to one another: two thermostats ar ranged for heat-responsive deflection in the same of said rotary member, said thermostats being mounted on one of said members and engaging said'other member at axially opposite sides of said rotary member so as to prevent said rotary member from rotating under its bias, one of said thermostats being arranged relative to said stop member so as to abut against it when thermally deflected leasing said rotary member for spring biased rotation, and electric heating means associated with one or said thermostats for causing it to deflect more than said other thermostat upon occurrence of a given release condition.

shaft remains virtually ineffective as regardsthe operation of the clutch mechanism because the clutch drum as well as the thermostatic clutch members are symmetrically arranged and hence statically and dynamically balanced with respect to the shaft. I A second possibility of shock transmission is given by the presence of the actuating plunger l8. However, a shock tending to movethe plunger 18 tangentially to the clutch drum will have the same effect on the balancing plunger 48. Since the two plungers act in oppositionon the clutch drum, the shock forces trans.- mitted by them will produce equal momentums and hence cancel each other as regards the efv fect'on the clutch mechanism. The third possibility is longitudinal acceleration due to a top or bottom blow, Fig. 1.' However this results in an increase in the frictional force between the drum and either the top or bottom bimetal discs. Consequently, the relay is virtually insensitive to high intensity shock forces without requiring the I presence of shock-responsive latching devices.

Being aware of the fact that devices according to my invention can be modified in various re-- 3. A thermostatic an ambient-temperature compensated relay comprising a rotary and axially displaceable member spring biased for rotation in one direction, two thermostats deflectable in the same axial direction and arranged 'at opposite axial sides of said rotary member, an axially operating spring disposed for normally holding said thermostats in engagement with said rotary member to retain it in opposition to its rotary spring bias, stationary stop means for limiting the heat-responsive axial motion or one of said thermostats inbrder to release said member, and heating means associated with one ofsaid thermostats for heating it in order to cause it to abut against said stop means upon occurrence of a given'release condition 4. A thermostatic and ambient-temperature compensated relay comprising a rotary and axial- 5. A thermostatic and ambient-temperature" compensated relay comprising a rotary and axially displaceable member spring biased for rotation in one direction, two non-rotatable bimetal discs arranged for heat-responsive deflection in the same axial direction and at opposite axial sides of said member, an axially operating spring a given amount thereby redisposed for normally holding said discs in engagement with said rotary member to retain it in opposition to its rotary spring bias, stationary stop means for limiting the heat-responsive axial motion of one of said thermostats in order mostatic relay comprising a shaft member having a radial projection, a drum member rotatably mounted on said shaft member, spring means for imposing a rotary bias on said drum member, two thermostatic discs arranged around said shaft member at opposite sides of said drum member for heat-responsive axial deflection in the same direction, one of said discs being firmly connected with said shaft member and the other being as a whole axially movable relative to said shaft member, an axially efiective clutch spring tending to hold said other disc toward said projection and against said drum member for retaining said drum member against the bias of said spring means, and electric heating means associated. with one of said discs to cause it to deflect more,

than the other upon occurrence of a given release condition, whereby said other disc is caused to abut against said projection in order to release said drum member for rotation under bias by said sprin means.

'7. A heat-responsive and ambient temperature compensated relay comprising a rotary and axially displaceable spring biased member, two thermostats axially movable in the same direction in response to heat and disposed for normally engaging said rotary member at axially opposite sides so as to prevent it, when moved against its spring bias, to perform a return motion under said bias, stationary stop means for limiting the heat-responsive axial motion of one of said thermostats in order to release said member, means for adjusting the axial position of said stop means relative to said rotary member, and heating means associated with one of said thermostats for heating it in order to cause it to abut against said stop means upon occurrence of a given release condition.

8.'A thermostatic and ambient-temperature compensated relay comprising a support structure, a spring biased movable member mounted on said structure so as to be rotatable and axially displaceable relative thereto, a stop member disposed in said structure and displaceable relative thereto in the axial direction of said movable member, means for adjusting said stop member in a, selective fixed position relative to said structure, two thermostats arranged for heat-responsive deflection in the same axial direction of said rotary member, said thermostats being mounted on one of said members and engaging said other member at axially opposite sides of said rotary member so as to prevent said rotary member from rotating under its bias, one of said thermostats being arranged relative to said stop member so as to abut against it when thermally deflected a given amount thereby releasing said rotary member for spring biased rotation, and electric heating means associated with one of said thermostats for causing it to deflect more than said other thermostat upon occurrence of a given release condition.

9. A thermostatic and ambient-temperature compensated relay comprising a rotary and 6. An ambient temperature compensated theraxially displaceable member spring biased for rotation in one direction, two thermostats defiectable in the same axial direction and arranged at opposite axial sides of said rotary member, an axially operating spring disposed for normally holding said thermostats in engagement with said rotary member to retain it in opposition to its rotary spring bias, stop means for limiting the axial deflection of one of said thermostats, adlusting means for selectively varying the position of said stop means in the axial direction of said member, and heating means associated with one of said thermostats for heating it in order to cause it to abut against said stop means upon occurrence of a given release condition.

10. An ambient-temperature compensated thermotatic relay comprising a support, a shaft member secured to said support and having a radially projecting stop, adjusting means for varying the position of said stop relative to said support in the axial direction of said shaft member, a drum member rotatably mounted on said shaft member, spring means for imposing a rotary bias on said drum member, two thermostatic discs arranged around-said shaft member at opposite sides of said drum member for heatresponsive axial deflection in the same direction, one of said discs being firmly connected with said shaft member and the other being as a whole axially movable relative to said shaft member, an axially eiiective clutch spring disposed between said support and said other disc and tending to hold said other dise toward said projections and against said drum member for retaining said drum member against the bias of said spring means, an electric heating means associated with one of said discs to cause it to deflect more than the other upon occurrence of a given release condition, whereby saidother disc is caused to abut against said projection in order to'release said drum member for rotation under bias by said spring means upon occurrence of a release condition depending upon the adjustment of said adjusting means.

11. A thermostatic and ambient-temperature compensated relay comprising a spring biased rotary member and a stop member axially movable relative to one another, two thermostats arranged for heat-responsive deflection in the same axial direction of said rotary member, said thermostats being mounted on one of said members and engaging said other member at axially opposite,sides of said rotary member so as to prevent said rotary member from rotating under its bias, one of said thermostats being arranged relative to said stop member so as to' abut against it when thermally deflected a given amount thereby releasing said rotary member for spring biased rotation, a resetting plunger movable tangentially to said rotary member and engaging the latter for transmission of motion, and electric heating means associated with one of said thermostats for causing it to deflect more than said other thermostat upon occurrence of a given release condition.

12. A thermostatic and ambient-temperature compensated relay comprising a spring biased rotary member and a stop member axially movsaid rotary member from rotating under its bias,

one of said thermostats being arranged relative to said stop member so as to abut against it when thermally deflected a given amount thereby releasing saicl rotary member for spring biased rotation, electric heating means associated with one given release condition, a. plunger movable tangentially to saiel rotary member and engagingthe latter for transmission of motion, and a secsaid rotary memher to render the relay substantially shockproof.

13.- An electrio relay comprising a spring biased rotary member, releasable clutch means for retaming said member in opposition to its spring bias, a contact aotzzating plunger engaging said member tangentially for transmission or motion, and a second plunger movable in parallelv to said first plunger and engaging said rotary member snced about said shaft and engaging for motion opposite to that of said first plunger, 1

said two plungers being approximately balanced relative to the ax member to render proof.

14. An electric of rotation of said rotary the relay substantially relay comprising a shaft, a

spring biased member rotatable about said shait,

shoclb w clutch means arranged symmetrically and ball said member for normally retaining it in opposition to its spring bias, electric control means for releasing opposition to its spring" bias, electric heating means associated with said disc for causing it to release said member a, con

tive to the axis of rotation of said rotary member substantially shockproof.

GEORGE C. ARMSTRONG. 

